X-ray and neutron structural study on water under high pressure and high temperature

Katayama, Yoshinori; Hattori, Takanori   ; Saito, Hiroyuki; Sano, Asami   ; Suzuya, Kentaro; Yagafarov, O.*; Chiba, Ayano*; Otomo, Toshiya*

Liquid water at ambient conditions has an ice-like, characteristic structure due to the hydrogen bonds between molecules. To study pressure and temperature dependence of the structure of water, we have carried out in-situ high-temperature high-pressure measurements on liquid water using synchrotron radiation at the SPring-8 and molecular dynamics simulations. The results revealed transformation from the ice-like structure to a simple-liquid-like structure. To investigate change in hydrogen bonds, neutron is an important probe. We carried out neutron diffraction measurements on heavy water at room temperature, 100C and 200C at 0.8 GPa using newly-built high-pressure diffractometer, PLANET, at J-PARC/MLF. Significant temperature dependence of diffraction pattern was observed.